Warm - Up 1. What is the process called when atoms are split? 2. What is the difference in reactions between a nuclear bomb and a nuclear power plant? 3. What are some advantages of nuclear energy? 4. What are some disadvantages of nuclear energy?

Chapter 18 Renewable Energy

Renewable Energy Renewable energy – energy from sources that are constantly being formed Solar Wind Water Earth’s heat

Solar Energy Sun - Medium sized star Nuclear fusion in the core Fraction reaches the Earth All renewable energy comes directly or indirectly from the Sun

Passive Solar Heating Sun’s energy directly heats Passive solar buildings – which way are windows (Northern Hemisphere)? Thick insulation

Passive Solar Heating Summer – sun in high in the sky Overhang cools Winter – sun low in the sky Sunlight enters windows

Active Solar Heating Sun’s energy is captured in collectors Roof mounted Liquid heated in collectors Heats water for home

Photovoltaic Cells Solar cells Convert sun’s energy into electricity Nonpolluting Small electrical current Hundreds of acres of panels to heat a small town

Solar Cells Extended periods of sunlight Energy stored in batteries

Wind Power Fastest growing energy source Cost effective Erected in 3 months

Wind Farms Windiest spots on Earth – generate more than 10X energy used worldwide Problem – transporting energy in rural areas to urban areas

Biomass Fuel Plant material, manure, or an other organic material used for energy Burning dung or wood Wood is renewable to an extent

Methane Bacteria decomposes organic waste – methane Bio-gas digesters: ferment manure Dung-fired power station: produces electricity Decomposition of trash

Alcohol and Ethanol Ethanol or alcohol Fermented fruits or agricultural waste Corn – U.S. Gasohol – blend of gas and ethanol

Hydroelectricity Energy from moving water Expensive to build Inexpensive to operate Last longer than fossil fuel plants Disadvantages?

Micro-hydropower Small streams No big dams Cheaper More remote areas

Geothermal Energy Energy from heat inside the Earth’s crust Pumps water or steam into a turbine U.S. in #1

Geothermal Heat Pump

Alternative Energy Energy sources that are still in development

Tidal Power Tide rises – water flows behind dam Tide lowers – water trapped behind dam Released and turns turbine Expensive

OTEC Ocean thermal energy conservation Differences in water temperatures Surface – warm Deep – cold Water boils at low temperatures in low pressure vacuum Boiling water  stream  turbine

Hydrogen Gas When burnt combines with oxygen – H2O Produced when electricity splits water

Hydrogen Gas Expensive to produce Pollution Must be compressed

Fuel Cell Fuel cell - produces electricity chemically Combines hydrogen fuel with oxygen from the air

Energy Efficiency Energy efficiency (in %) = useful energy out//energy in x 100

Cogeneration Production of two useful forms of energy from same fuel source Waste heat from industrial furnace to turn turbine

Green Gadgets Video Clips